We have devised various screening procedures that are being used in attempts to isolate lysogenic and non-lysogenic bacteriophages active against Neisseria gonorrhoeae. These phages will be characterized in terms of host range, serological specificity and nucleic acid base composition. Methods for propagation and assay will be developed to the point that the phages can easily be used by clinical laboratories for typing purposes. We will also attempt to further characterize the N. gonorrhoeae transformation system in terms of the possible participation of a competence factor and in terms of the importance of pili to the achievement of the competent state. Eventually we hope to achieve transformation of avirulent N. gonorrhoeae (types T3 and T4). In a related study we will continue to characterize the bacteriophages that we have isolated that are active against N. perflava with respect to stability, methods of assay and other parameters. These phages represent the only models available for the study of gonococcus phages in the absence of the true gonococcus-specific phages themselves. We will also use DNA isolated from N. perflava phages in experiments designed to obtain a transfection (infection with phage DNA) system for N. perflava. Shoul we obtain this homologous transfection system we will attempt to transfect N. gonorrhoeae using N. perflava phage DNA and in this way perhaps overcome the species specificity exhibited by these phages.